QUICK NITROGEN TESTS FOR USE ON BEAN AND SWEET CORN CROPS IN QUEBEC (CANADA)

Experiments and a survey were conducted to assess the potential of quick tests for evaluation of N status of bean and sweet corn crops grown for processing in Quebec (Canada). Merckoquant test strips and the Nitracheck reflectometer were used for NO₃-N quantification. Nitrogen fertilization was applied at 5 rates. N_min contents at sowing were relatively low both in commercial fields or experimental plots. NO₃ thresholds in sap at 3 weeks after sowing could be used as a way to quantify topdressing N applications but this NO₃ content can vary from year to year. Chlorophyll-meter readings were not correlated to N application at a crop development stage early enough to adjust side dressed N applications. Bean was shown to leave a higher N_min after harvest than sweet corn and may produce a higher N loss to the environment.